My post on Computers passing Turing test sparked an interesting Twitter exchange with Aleš Golli about consciousness and next frontiers for computers after they'll match human performance in cognitive tasks. We, the humans, might be able to wave away advances in artificial intelligence in domain of object or speech recognition, but dismissing a computer with own personality and aware of itself will be much harder to do, as the movie Her so vividly demonstrated. Unfortunately, consciousness has so far eluded detailed scientific scrutiny and there's very little known about this phenomenon except that it is much less magical than we imagine. The predominant model of consciousness in our society is that of homunculus - a small person living in our brains that is our true personality and which uses our body for perception and action. While simple and matching our self-perception, such explanation only reduces the original problem to equally difficult problem of how homunculus functions and doesn't account for anosognosic disorders and effects various chemicals have on our self-perception. The humunculus explanation is part of dualistic worldview which pertains that domains of mind and body are separate, with mind lying in the divine sphere and body in the earthly sphere. The predominance of this worldview exposes itself whenever we refer to essence of human personality with the term "human spirit".
Scientific scrutiny of consciousness has started only recently and not much is known yet. But study of brain lesions, children development, and experiments on animals have shown that consciousness is amenable to scientific study and it's not such on or off phenomena as healthy adults like to imagine but varies in degrees and it's susceptible to external influence. If you're interested in the subject of consciousness I highly recommend reading Descartes' Error by Antonio Damasio, The Man Who Mistook His Wife For A Hat by Oliver Sacks, and The Mind's I by Hofstadter and Dennett.